The invention concerns an adjustment table for aligning a body in a horizontal plane.
When creating electrical structures (circuits) on semi-conductor discs (wafers) using lithographic processes, it is necessary to position a wafer exactly in a horizontal level (orientation) relative to a mask. A similar problem is also faced during other processing techniques involved in manufacturing, processing or reworking of wafers.
While it is possible to control the alignment of a wafer in the X and Y direction within a plane using a microscope, there are severe design problems while fitting the wafer on a corresponding holding unit that allows the desired flexibility of movement in the X and Y direction and also ensures that the wafer is finally fixed in the corresponding final position.
The invention is supposed to bring to light such a possibility.
The invention is based on the following concept. A suitable adjustment table must have at least two movable parts that can be adjusted in at least two different directions (x, y). In this way, it is also possible to control any desired end position within the maximum displacement paths, if required with an angular displacement (turning). The movable parts should further be guided towards a stationary part, which helps in positioning the movable parts within a horizontal plane on one hand and creates a possibility of vertical adjustment for the entire equipment (the adjustment table) on the other.
The invention also is further based on the concept that the individual parts of the adjustment table should be more or less xe2x80x9cencased in each otherxe2x80x9d so that the first movable part adjacent to the stationary part on the inner side can be moved in a horizontal direction and a second movable part arranged therein can be moved in horizontal direction perpendicular to it.
Here, the components movable in X and Y directions should geometrically match each other in such a way that each movable component can be moved in an exact linear line of movement in a horizontal plane.
Further, it is necessary to plan for equipment that fixes the movable parts in the desired final position.
The invention in its general form concerns an adjustment table for aligning a body, for example a wafer, in a horizontal plane, the adjustment table having the following characteristics:
an external frame,
an intermediate frame movable in a first horizontal direction (x) in the external frame along a first path (Xges),
a holding unit for the body movable in a second horizontal direction (y) that is perpendicular to the first horizontal direction (x) in the intermediate frame along a second path (Yges),
an intermediate frame that can be positioned relative to the external frame via a first adjustment device pivoted/hinged to the intermediate frame at a freely definable position along the first path (Xges), and
a holding unit that can be positioned relative to the intermediate frame via a second adjustment device pivoted/hinged to the holding unit at a freely definable position along the second path (Yges).
In other words, the external frame that is not movable in the horizontal plane supports an intermediate frame that can be moved along the entire length (Xges) of the first path in the X direction.
The intermediate frame correspondingly supports a holding unit that can be moved across the entire length (Yges) of the second path within the intermediate frame. The path lengths of the first and second path can be the same, for example 5 mm. Such xe2x80x9cinterplayxe2x80x9d is generally adequate for the given area of application for positioning the wafers in a suitable device, for example to position them opposite a corresponding mask.
With the help of the adjustment devices, the intermediate frame and holding unit can be fixed in desired positions along the first and second paths, depending on the application. Additionally, a section of the holding unit used for supporting the wafer can be arranged in the horizontal plane in such a way that it can be turned.
The intermediate frame can be arranged on a corresponding supporting surface of the external frame. Thus, the external frame can have a tongue on the inner side, on which the intermediate frame lies all along its periphery close to the border. One embodiment envisions the arrangement of sliding elements for improving the sliding properties between intermediate frame and external frame.
A similar arrangement can also be made between the intermediate frame and the holding unit.
According to one embodiment, the sliding elements have balls or ball casters that can be fitted in groove-like recesses of corresponding surface sections of parts that move relative to one another (external frame, intermediate frame; intermediate frame, holding unit). It goes without saying that the arrangement of the corresponding components is preferably done in such a way that the components that are to be moved in relation to one another are at a short distance from each other, in axes next to the sliding elements. The direction of movement (x or y direction) of the corresponding components can be supported by arranging and fashioning sliding elements.
Another embodiment provides for the movement of the intermediate frame along a base that connects peripheral protruding frame parts of the external frame. In this embodiment, which is also shown in the following figure, the external frame has the form of a xe2x80x9ctroughxe2x80x9d.
The base of the external frame will thus not only support the sliding elements of the intermediate frame, but also support the holding unit arranged within the intermediate frame.
A defined movement of the given components in X or Y direction is also possible by connecting the external frame and the intermediate frame with each other with springs. These should at least be movable in the direction of the first path. Likewise, the intermediate frame and the holding unit can be connected with each other with springs that at least move in the direction of the second path.
In the first mentioned embodiment, the springs can be mostly arranged perpendicular to the direction of the first path whereby they run in the same plane and are arranged in a space formed between the external frame and the intermediate frame.
Similarly, in the second embodiment, the springs can be mostly arranged perpendicular to the direction of the second path but in the same plane and are arranged in a space formed between the intermediate frame and the holding unit.
In order to support the desired movement in X and Y direction it is recommended that the external frame, intermediate frame and the holding unit be formed in such a way that they more or less show a rectangular external contour in the view.
The external edges of the component running in the direction of movement of the component and the corresponding surface sections of the adjacent components must guide in an exact linear manner. For this reason, they are generally formed in the shape of flat surfaces.
The component sides that run perpendicular to the direction of movement of the respective components can be designed in any desired manner. For example, these external sides can have an outwardly extending projection in the center, on which two springs are fitted that run in different directions from this projection at a distance from one another, the other end of each spring being connected to the corresponding component. This arrangement of two springs, each on opposite side of every movable component, supports the exact linear movement of the respective component in the X or Y direction. A more detailed description of this model is given below with the help of the drawings.
The projection can also be used for creating a fulcrum point for the adjustment device as will be described below in detail with the help of the drawings.
The adjustment device can comprise a motor or gear unit. The adjustment device that influences the intermediate frame (from the outside) can be fixed on one location, for example, on the external frame, whereas the adjustment device that influences the internal holding unit should be capable of being guided perpendicular to direction of movement of the holding unit and thereby of the intermediate frame. The device can be directly fixed on the intermediate frame. Another option is to arrange the device in a corresponding recess of the external frame, which allows the displacement of the adjustment device along with the intermediate frame.
Other features of this invention arise from the features of the sub-claims and other application documents. The following description of Figures also indicates the features of the invention that can be realized in every possible combination.